Subwoofers.... one 10" or two 8"?

I'm looking to fill out the bottom of my simple 2 channel system  (Musical Fidelity X-Ray CDP through Peachtree Audio Grand Integrated amp to a pair of Mirage OMD-15 full range speakers).  I occasionally will play the TV audio through the system for movies, but not interested in an HT setup. Music is the prime focus. The room is "medium" size.  I know that will not give the deep bass feel of a 12", but the difference should not be too great, and a 12" may be overkill for that room.  I've also considered getting two 8" subs to keep the sound balanced between the left and right channels. I think the  8" may be enough bottom for my room and tastes. I'm on a budget so getting a pair of anything bigger than 8" may not be in the cards.

Any opinions or suggestions as to whether I'd be better off with one 10" or two 8" subs?

Hi larstusor,

The 3dB-down point at 33 Hz on your Mirages give you some room to work with, so you might end up wanting to leave their signal unmodified and just "add" the sub(s) at a reduced output level, so to speak. Or you can think about crossing them over to the Mirages and reducing their burden if need be...either way would be ok. As for 8" vs 10", it may come down to a toss up, really...two eights might be quicker, but one ten should go deeper. As far as balancing the bass between the two mains goes, it all depends on what frequency range you end up crossing them in at. At about 60 Hz or below the summing of the bass effect will be pretty much nil. On up to around 100 Hz starts audibly introducing the summing effect and above that frequency it starts to become more and more obvious, IME.

Maybe the bigger question, especially in the price range you're considering, is just how flexible the integration is going to be with your mains. Maybe the number one reason for buyer remorse with subwoofers is not that they don't go low enough, but that they don't offer sufficient control over the right parameters to blend properly, i.e. invisibly enough. I'd much rather go with 2 eights that offer flexibility than any ten that doesn't. In fact, personally, as far as I'm concerned, a sub that isn't offering sufficient flexibility isn't really a sub at all...just a waste of time and money, really. If you can't find one of those in whatever price range you're considering, my advice would be to pass until you can maybe move up the ladder just a bit. That said, there are good ones out there. Just look at things like crossover frequency selections...the more individual settings the better...just 2 or 3?? gotta hope like hell you get lucky with one of them or you're screwed. Digital parameters are worth looking for if you can find them, since they offer a good bit of sonic transparency in the bass region, usually without much drawback, especially if you're not crossing into the mains. But, you may have to either search a while longer for that or be prepared to move up the ladder.
Hope that helps
I think whatever you decide you want to go with one sub, not two. Here is one to consider:
With all due respect to gdhal, I went with a pair of SVS SB1000 to fill out the bottom end from some Silverline Prelude Pluses.  The Pluses have surprisingly good bass for the size of their drivers.  If all I listened to were, say, acoustic jazz they would be completely adequate.  BUT things being what they are, I wanted a little more so ordered the SB1000s.  The Silverlines run full range and the subs are connected via speaker level input from amps.  The subs are positioned next to the floor standers and crossed over at around 100 Hz.   I listen about 8-10' from speakers that are 2-3' out from front wall in a ~19'x21'room with an open back wall (i.e., wall behind the listening position).  Subs disappear but give Tony Levin's bass a nice growl and make Bela Fleck's Cosmic Hippo sound amazing.  The system is posted if you want to take a look.  Good luck in your decision.
On several occasions I have demo'ed a wonderful 10" REL and 8" Sunfire. Both will fill the OP needs.
The two subs I'm looking at are the NHT Classic 10 and the Energy ESW8. Both of these have fully variable crossovers and they both have the black piano finish that would match my mains; not necessary but a bonus, all other things being equal.  Is there any advantage to connecting to the sub out of high level speaker outputs as opposed to going from low level preamp outs?
In theory, if  you have the time and space to find the optimum location for the subs, 2 assymetrically placed subs will usually yield a smoother combined response.

Having said this, a 10" sub is a lot better than an 8". The surface area a 10" driver can move is close to that of 2 x 8" woofers, so distortion, low frequency and dynamic range all get much better with those 2 extra inches.

Looking at the review though, I would think an EQ is a better solution than a sub for you.  Or an EQ and a subwoofer. I'm actually really surprised to see measurements that show such a difference between the treble and bass (10 dB!) That's kind of huge. Adding more bottom end weight may be the worst possible thing.  The only way to tell is to measure in room though.


Try both ways of hooking up your sub(s) and hear which sounds best to you.  I can run the SVSs with either high level or line level inputs.  I had thought line level was the better way to go (running floor standers full range and using a 2nd set of preamp out connections to the subs) but found a speaker level connection sounded better to me...thought things sounded "fuller".
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I believe, this cannot be answered in general terms. There would be both advantages and disadvantages of both arrangements. Without knowing much about your preferences, your speakers and room, it really would be a very wild guess. But if you want one - I would go with two subs if you have enough room to correctly position them. The reason for this being that they should be able to better integrate with your main speakers, theoretically.
Yes, 8" perhaps cannot be true subwoofers but they certainly can be true woofers, and this just could be enough.
A phone with a calibrated mic does much better than the SPL meters of yore for consumers.

The Dayton Audio imm-6 ($24) with something like the Android Audio Tools is really very very good.

Doesn't come up to the level of Room EQ Wizard or OmniMic, but for basic calibration it's hard to beat.


Two is almost always better than one but I{'m not so sure that rings true with 8". It depends on the room.
I had two sunfire 8" yrs back with maggies i loved it fast and crisp . I’ve had alot of subs over the yrs from 8"-15 different brands and applications. ( rel velo sunfire svs nova ) Room characteristics play a big role imo . Bass traps and treatment . I still think sunfire makes a great sub for the bks 10-12" about a g or so . 2 good 10" and proper room treatment will be tight and just rip when you want it in a med room .jmo
Thanks all for the good information and suggestions.
I owned a pair of OMD-15s for five years and had a pair of Mirage MM8 8” compact subs with them for at least three of those years. The OMD-15s are pretty picky about getting decent bass. It requires a solid (e.g., masonry) floor and reasonable proximity to room boundaries to get meaningful bass below around 42 Hz. My pair was in the living room on a suspended wooden floor and I couldn’t get the wide cones to penetrate the carpet all the way to the floor. I thought about getting Soundocity outriggers to aid in seating the speakers, but I came across some closeout specials for the MM8s and bought them instead.

If I’d had more money I might have gotten a couple of bigger subs, but that’s what I got and the advantage of the MM8s is that they were *very* quick and blended easily with the OMDs. The downside is that they were only good down to around 36 Hz. If I could have gotten a sub or two that extended into the 20s, this rig would have really excelled on a wide range of music including one of my favorites—bombastic large-scale orchestral pieces such as The Planets, Scheherazade, etc.

Which sub size you go for depends on how much grunt and bass extension you can get out of the OMD-15s. Can you spike them clear through to the floor and ensure that there’s no wobble? Can you move them around and find a balance between imaging and bass reinforcement from room boundaries? Then they can reach into the 30s and you would probably want a 10” or 12” sub and use a lower crossover point. If your bass is disappearing around 45-50 Hz you may need to stick with a pair of 8-inchers to get a good blend at a higher crossover point.

A third option if you can spring for it, would be to get a pair of Sunfire HRS8s, an 8” subwoofer with a very high-excursion driver that can realistically reach down into the 20s.

The JL Audio Dominion d108 is another 8" sub that reaches down to around 30 Hz.
My OMD-15s are sitting a a very solid hardwood floor over a plywood sub-flloor  built on a concrete slab.  Contact between the speakers and floor is rock steady.  I wonder if I'd get more bass by putting the speakers on feet to isolate from the floor.  It's hard to imagine an 8" subwoofer going down into the 20s.  How does the HRS8 sound at moderate listening levels?
My 8" REL t108 II is absolutely a true sub, and I use it with a REL 10" which is from the same era. Speaker size is less important than the overall design of course, and although the 8" REL is rated to 23hz or so, it works as a fine musical sub. I recently bought a mint Mackie HRS120 sub designed for studio use (to use in my studio…) with a 12" driver and a 12" passive radiator, it weighs 95 lbs, has a 400 watt A/B amp and its -1.5db point is around 19hz with very low distortion. Used, under 300 bucks. Yeah.
x2 on the above comments.rels are good subs.Although i am often perplexed why I don't see more people running the better sunfires they a great subs.The 8" sunfire back in the 90s was a beast for its size i had 2 with mg3a and cj it was great (treated room).I have a hsu 12 and it will peel your face off if you want it too.It smokes the velo 15" i have in the ht room ..Again and again i say it invest in treatment it will change the game in your room...gaarrunnttteeeed . lol any good sub will sound way better with treament I personnally have seen it again and again. again my humble opinion..
Well, I've been strongly considering trying to stretch my budget and get an SVS SB-1000 (piano finish) but I came across an excellent deal on a "like new" Sunfire HRS8 and, based somewhat on the praise for it on this forum,  I bought it.   I will play around with the set up and try to dial it in.  Meanwhile, I'll keep my eyes open for another good deal on a second one. If the right deal comes along, I'll have two HRS8s for a few bucks more than one SB-1000.  Time (listening) will tell if I went in the right direction.
larstutor wrote:
My OMD-15s are sitting a a very solid hardwood floor over a plywood sub-flloor built on a concrete slab. Contact between the speakers and floor is rock steady. I wonder if I'd get more bass by putting the speakers on feet to isolate from the floor. It's hard to imagine an 8" subwoofer going down into the 20s. How does the HRS8 sound at moderate listening levels?
Are you using the Mirage cones for seating the speakers on the floor? Otherwise if they're just sitting flat on it that could reduce the bass. My mid-'90s M5si's have bass wherever you put them. The OMD-15s are capable of low 30s bass, but can drive you crazy trying to find it.

When it comes to sub power and depth, diameter isn't the only factor in making a strong wave; excursion matters, too. Total volume displacement is the diameter times the maximum excursion. Bob Carver and Sunfire practically invented the high excursion subwoofer driver, with that big reverse roll surround that would allow a 1" excursion when 1/4" was still considered extreme. Of course going up in diameter *plus* the high excursion makes it deeper and stronger yet, but Sunfire claims to extend into the 20s and the reviews I've read of their subs indicate that they tend to go as deep as they claim.

I'm sorry if I gave the wrong impression; I haven't heard the HRS8 so I can't comment on room-filling capability. But I have some reason to trust them as I've heard other very compact Sunfire subs. 

As for the NHT Classic Ten and Energy ESW-8, I think you're shooting too low. The Classic Ten was designed to mate with a dual-woofer tower and the ESW-8 with the Energy Take 5 miniature system. If you want to add a real bottom end to the OMD-15s (which I think is worth doing), you'll have to up the ante unless you luck into a deal. 

Consider the SVS SB-1000, a 12" sealed enclosure (best for music) powered sub that's $499 in black ash or $599 in piano black gloss. This one should be plenty fast and elevate your OMD-15s to a higher (and lower :-) ) level. Lots of positive professional reviews.

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The take away is that SPL is key. And fortunately most music doesn't contain much bass.
Exactly, especially given that 2-channel music is the OP's primary use of the system. I have used a Mirage LF-150 (10" x 150w) and an LF-100 (8" x 100w). Believe it or not, using the Stereophile test & demo CD, both subs produced clean, clear sub-30 Hz warble tones easily audible from the listening position about 8-10 feet from the subs. They might not be the best thing for crashes and explosions for HT in a large room, but for 2-ch. stereo they did surprisingly well. The more upscale sealed w/ passiave radiators Mirage MM8s do better (on transient response, clarity, etc.) but don't go as deep as even the modest LF-100.

I've also heard the SVS SB12 with full-range speakers in a fairly large media room and it acquitted itself well on 2-channel music. I think it's a good candidate for the OP. 

How good are Dynaudio subs? Anyone tried?
I have had over the yrs probly 10 different subs . The original 8" sunfires with my mg3a sounded killer .. I had a pair  of the better 10" velos granite looking base with kefs they were imo not as good as the sunfires anong other velos, a single rel few yrs back 12" it was nice i have a hrs 12" sunfire on spikes now it gets boomy if its not placed right . I would like 2 10" in my room but honestly there are many times i dont even use the sub. There are many things at play with a sub regarding placement , straddling corners etc. but i never knew how good the low end sounded until i started working on room acoustics . Regarding small subs and high distortion i can't comment , i only know what sounds good in my setups over the yrs . The only 15" i ever had is the velodyne i have a model i can’t remember at the moment it was around a g retail is in my ht room its huge and rattles the house but tight is it not . 2-8" = 😬 2-10" = 😃 2-12" = is overkill in a small med room . Jmho .. Treat that room with some bass traps of some kind you’ll be surprised.👍😄
It is good to read what I have known for many, many years now regarding REL and Sunfire subwoofer(s).
This set up is not in a dedicated listening room but rather in our living room and  I don't think my wife is going to stand for bass traps. Anyone else experience a similar problem? (lol)

Based upon your experience with OMD-15s, what length spikes or feet would be appropriate to enhance the bass?  How high off the hardwood floor should I go?
 I get it..... my wife married a career musician and motor nut so she gave up in the beginning when it came to the garage, guitars, amps and me stealing the spare room for dedicated audio.( studio is 100yrd from the house lol) In the ht room "family room" i am working on the treatment now it rings bigtime (slap echo) 24'x28'x17' vaulted ceilings. she is down because she can hear the difference .If you can sway her try somebody like gik and just browse thru they can take pics and imprint them on the panels.Who can say no to a family pic? lol. I have and still remain a fan of the better sunfires and honestly i may be in the few but i feel a smaller driver is faster and more accurate.Thats why i dont have big drivers in my spkrs like many . Sometimes if not almost all the time when ya take a crisp tight spkr and put a larger sub with it there is a distinctive separation between them imo .i think when you get that hrs8 you will be shocked it throws like  1.5" ! mess around with it .I know the purist are going to interject but straddle a corner facing out ,a foot or two ,try phase switching,and god forbid lol turn it around about two feet from a corner and face it .try it along the wall close and a cple feet out.these changes will be significant some will be boomy as hell somewhere in there it should just melt away in your system .If your are like "dam theres the low end i'm looking for maybe you can mark it somehow and only place it there when the wife is away and have a serious session.i used to do that in one of my old setup yrs ago. Get another 8' sunfire it will be tight and rip in all but the most demanding situations and there tiny.( wife approved).although for me i would prefer two 10" in the perfect setup .sorry but your setup is limited by different obsticles with all due respect. I am lucky to have a 13'x16'x10' room. the sunfires are easy to sell if you choose a different path ..jmho
good luck
I want to clear up something i said. There are some killer 12" and 15" subs like the jl audios but thats a different topic and way above the money you want to spend ..
respect and good luck

Thanks oleschool, I will certainly check out your recommendations.

There is one sub using 8" drivers that breaks a lot of subwoofer rules. It is the GR Research/Rythmik OB/Dipole Subwoofer. Three 8" woofers per sub, mounted not in a sealed or ported enclosure but in an Open Baffle "H-frame". Exceptional sound quality. The sub is also available with 12" drivers, providing greater extension and SPL.

By the way, Sterling Sound in NYC just added two more Rythmik F15HP subs to their mastering-house monitor systems, bringing their Rythmik F15 sub total to nine. Anyone not including the Rythmik Direct Servo-Feedback offerings in his/her sub search is making a huge mistake.

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The most effective use of subs are to cancel nodes in the room.  By doing proper placement of 2, 3, 4, subs, you actually make the mids and highs cleaner and clearer.  The result of proper subbing is not to hear the subs as their own speaker (pumping booming lows into the room), but rather the effortless reproduction of your recordings.
Yep thats why i am a fan of treatment 
Here’s a thought. I suggest building your own subs. I just ordered 2 Dayton audio 12" Sub drivers and all the other items to build them (cabinets, stuffing, etc.) I will be using them in a 14 x11 x8ft room to supplement the (ahem) polite bass of a set of Ascent i speakers I bought used. I am using the Gallo sub amp, but there are many choices in sub amp available. From $100-$1000. Some of these amps have EQ built in as well. I am using a dSpeaker Antimode 2.0 to EQ the bass.
The Gallo amp pushed my Gallo reference 3.1 to beautifully powerful, fast and accurate bass. I am hoping the dual 12s will do the same.

Get at least one 12. Make sure it is sealed, not ported. Give it power and judicious EQ ,and you will be in heaven.

Remember- Bass production needs air movement. Period! Go with two 12s, and don't look back!

As for the myth of 12s being slow- pish posh. The reason bass seems slow is because of overhang, room modes/nulls, and poor sub placement. This is where good EQ can help. Good room treatments help here as well.
Good luck, and have fun!

The latest Music in the Round from Stereophile features the use of two JL subs, and charts showing how they fill in.

Still, it's not unreasonable to get one very good sub, see if you need two. :)

I most certainly am more than happy with 1 Hsu 15" sub. My listening space does not lend itself well to characterization and I have bass traps where they need to go. YMMV.


        I have an  Sunfire hsu12 .( az cable rca's from preout) I am pretty impressed with it in general .Althoough i did put 3 . 1.5" audiopoints under it which just made a real deal difference in the overall sound ).I would consider grabbing another, which is somewhat shocking to me with it being a 12"in the grand price range . i have generally preferred a pair of 10".If i had the money i would buy the jl audios probly 10". For yrs we tauted there power in audio apps and boats etc. There new subs are serious but are like 3-5k a pair.The sunfire ,svs rythmic etc would much less.
       Like i said Larstusor hook that 8" up and see what you get then let us know whats happening (easy to resale that sub).
       Also op  has limits on treatment and wife constraints as many do
.      Eric
 Although i do run a big velodyne 15" in my ht room its huge front ported. that hsu has to rattle the walls,my velo is nuts just not a good audio sub imo ..i would go sealed myself
Dealer alert;   Current velodynes are sealed subs and are designed to play very low frequency 20 and below).  I use 2 10"'s for my room (dd10+ series ) which is 28x30 and 15 foot ceilings, which is a lot of cubic feet. 
I cross them over at 40hz from my TAD CR1'S.  
I probably should have gone with 12's or 15's but wanted to keep form factor as small as possible.   
I would suggest to OP that he buy one high quality 10"sub then add another as funds allow.   This way he'll have deep bass with one, then smoother bass when he adds the second. 
Anyone in NYC that wants to hear the velodyne dd10+ series contact me at Triodepicturesound.      
If you can phase the sub perfectly to the mains you can get a lot more impact from even a small sub. This requires a sub with a continuous phase adjustment. (Not just 0 degrees or 180 degrees.) If your prepro can’t set a delay for the mains the best you can do is time align the sub 1 cycle late which is totally acceptable. Check:
Play a pure tone at the crossover frequency with cable polarity reversed on main, dial phase on sub till you hear the null at listening position. Now perfectly out of phase. Switch to correct polarity on cable to main and now is perfectly in phase. Can’t overemphasize the importance of time alignment to SQ. Consider that a crossover or low pass filter at say 12 db per octave gives very large area of overlap. (40 Hz to 80 Hz is 1 octave. 60 Hz to 120 Hz is 1 octave) If the timing is out of alignment there is distortion of all the sound waves over a wide frequency range (partial cancellations and partial additions within each sound wave). Sounds like hell. Anyway, I have several systems going and several really good subs. Needed a sub for a 2 channel setup so I got a single 8" JL Audio Dominion D108, Just to add a little bottom to my "full range" Revel Performa F206s. Totally did the job in a 17’ x25’ room. Couldn’t believe it. Didn’t want to believe it (cause I wanted to justify a bigger sub purchase) Was not great until I phased it in however. Go ahead and scoff ye unbelievers! Went ahead an got a Revel Performa B110 sub anyway because it was prettier and the price was ridiculous. But can’t really say the resulting SQ is remarkably better, even though It does go a little lower. Set up properly the performance of a pair of JL Audio Dominions would beat any 10 sub that was set up improperly IMHO. :)
But them ain’t your grandpa’s 8" subwoofers.

I have tried both, with varying, but excellent results with each.

For 25 years, I had some six foot tall electrostatics which originally had very sloppy cone subs. I also had a pair of NHT subs I hated.

I found some Peerless 8' and 10" sandwich cone subs, 8" for the

stats, an 10' for my B&Ws.

I really preferred the 8's, but they did not have the output I need for the  B&W's, so they went away with the electrostatics.

I have since upgraded these subs and use matching amps and preamps

for the mains and subs. After years of tweaking, the subs now reside between the B&W towers, time aligned with rulers. of course. This definitely sounds better on music than any subs my audiophile friends have brought by, 'though not as loud due to my (only) 125/250/400 (@8/4/2 ohms) stereo amp that drives them. 

Due to "group delay" sound impulse leaves the sub usually 8-10 msec later than it leaves the main, even though the electrical impulse hits the sub and the main at the same time. So must be aligned by ear. Using just distance measurement doesn't work. Used to think there was something wrong with my autocalibration when it consistently made sub setting farther away than the actual measurement. Check:
Someone please explain "time aligned"

That's a huge amount of "group delay." I think you are confusing that sub's are often located several feet behind the mains.

As for aligning by ear, great googly moogly no! :) It's far easier, faster and more accurate to fully align with a tool like OmniMic or AudioTools or Room EQ Wizard than by ear! :)

Assuming the room modes are dealt with, the second stage in integrating a sub are to integrate it with the main speaker. This runs into the same issues a speaker designer would have in blending one driver with the next. Meaning, crossover slopes and phase alignment to provide a seamless transition from the subwoofer to the main's output. You should not be able to tell by looking at the frequency response where the sub ends and mains start, it should appear like 1 single speaker.



It means a lot of things, but in general it means making sure that each driver you are listening to blends seamlessly with others despite being located at different distances from the listener.  It matters in multi-way speakers as well as in integrating a subwoofer with a main speaker. This really is "phase alignment" but in use it's often called "time aligned." 

In flat baffle designs, each driver has a different acoustic distance from the listener. Phase alignment means you've taken that and the phase of the crossovers into account so that the frequency response has no dips/valleys where they meet.  Here is an example from a speaker I designed, the LM-1.  Look at the second and last chart for more information. 

At it's most stringent, time alignment may mean having a perfect impulse or step response.  Van DerSteen is famous for this type of design.  Look at the step response in Stereophile's review of the Seven and compare it to the LM-1.  Thiel is also a manufacturer that specialized in time-alignment.



Hey eric 
. Aren't  reflection points playing a big role there also . When i used treatment on the points . The ole mirror reflection spot gik talks about it helped immensely. Op cant run treatment though 

Um, not sure the context, but true subwoofers have no real reflection points, the waves are so big that a reflection point would be around 10’ wide. At the mid to high frequencies where the wavelength is near or smaller than the driver dimension, sound travels like rays, so reflection points in a room matter a lot and are easy to treat with conventional panels and diffusers.

On top of that, most panels are completely ineffective below 300-400 Hz. Instead we rely on bass traps placed in corners where the maximum pressure points occur. Even a lot of "bass traps" don’t go much lower than 120 Hz, and below that is where the big issues occur. In this area, the GIK Soffit traps are unbeatable for effectiveness and cost. 


Your 8/13 2:27AM post seems very helpful.  THANK YOU.

I'm planning to try it integrating SVS SB1000s with Silverline Prelude Pluses that claim a lower end of mid 30s Hz.  

For anyone interested, an on-line tone generator is available at the link below.
Eric sorry i was speaking in broad terms like mids etc I suggested gik bas traps i use them and with a few other panels an diffusers it changed my game . Gik was just saying in general terms have a freind hold a mirror for you against the reflection wall until you see your speaker and start by treating that area with a panel etc . Obviously not accurate for all app my speakers are 4’ from the side walls corners are trapped . This all becomes meaningless if treatment is not an option
    Ghosthouse just curious why the svs no gripe or pro for it just curious for your decision over others
Hi Eric,
Beg to differ. Easiest and most accurate is the method I described very briefly. All you need is: play a test tone at the crossover frequency with reversed cable polarity at the speaker, listen for the null as you adjust the phase, correct cable polarity and done.. Don’t want to write a chapter on it so I posted a couple links. "Soundoctor" Barry Ober, tech support at JL Audio sells a disc for $20 with test tones and a variety of other tools for optimizing subwoofers, along with instructions for the why and how of it.

Um, yeah if that’s all you are trying to do. However you are not guaranteed accurate amplitude or phase matching above and below that point.

I’ll give you that it’s quick and good enough for many, but it's hardly comprehensive.